feat(zrpc): migrate kube resolver from Endpoints to EndpointSlice API

* Replace core/v1 Endpoints with discovery/v1 EndpointSlice in event handler
* Update handler logic to iterate over EndpointSlice.Endpoints[].Addresses[]
* Switch informer to watch EndpointSlices using label selector "kubernetes.io/service-name"
* Retrieve service port from the first EndpointSlice port when not specified
* Rename constant `nameSelector` → `serviceSelector` for clarity
* Improve error handling for missing EndpointSlices

Signed-off-by: soasurs <soasurs@gmail.com>

Author: soasurs

zrpc/resolver/internal/kube/eventhandler.go

@@ -5,7 +5,7 @@ import (
 
 	"github.com/zeromicro/go-zero/core/lang"
 	"github.com/zeromicro/go-zero/core/logx"
-	v1 "k8s.io/api/core/v1"
+	discoveryv1 "k8s.io/api/discovery/v1"
 	"k8s.io/client-go/tools/cache"
 )
 
@@ -28,20 +28,23 @@ func NewEventHandler(update func([]string)) *EventHandler {
 
 // OnAdd handles the endpoints add events.
 func (h *EventHandler) OnAdd(obj any, _ bool) {
-	endpoints, ok := obj.(*v1.Endpoints)
+	endpoints, ok := obj.(*discoveryv1.EndpointSlice)
 	if !ok {
-		logx.Errorf("%v is not an object with type *v1.Endpoints", obj)
+		logx.Errorf("%v is not an object with type *discoveryv1.EndpointSlice", obj)
 		return
 	}
 
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
 	var changed bool
-	for _, sub := range endpoints.Subsets {
-		for _, point := range sub.Addresses {
-			if _, ok := h.endpoints[point.IP]; !ok {
-				h.endpoints[point.IP] = lang.Placeholder
+	for _, point := range endpoints.Endpoints {
+		if len(point.Addresses) == 0 {
+			continue
+		}
+		for _, address := range point.Addresses {
+			if _, ok := h.endpoints[address]; !ok {
+				h.endpoints[address] = lang.Placeholder
 				changed = true
 			}
 		}
@@ -54,20 +57,23 @@ func (h *EventHandler) OnAdd(obj any, _ bool) {
 
 // OnDelete handles the endpoints delete events.
 func (h *EventHandler) OnDelete(obj any) {
-	endpoints, ok := obj.(*v1.Endpoints)
+	endpoints, ok := obj.(*discoveryv1.EndpointSlice)
 	if !ok {
-		logx.Errorf("%v is not an object with type *v1.Endpoints", obj)
+		logx.Errorf("%v is not an object with type *discoveryv1.EndpointSlice", obj)
 		return
 	}
 
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
 	var changed bool
-	for _, sub := range endpoints.Subsets {
-		for _, point := range sub.Addresses {
-			if _, ok := h.endpoints[point.IP]; ok {
-				delete(h.endpoints, point.IP)
+	for _, point := range endpoints.Endpoints {
+		if len(point.Addresses) == 0 {
+			continue
+		}
+		for _, address := range point.Addresses {
+			if _, ok := h.endpoints[address]; ok {
+				delete(h.endpoints, address)
 				changed = true
 			}
 		}
@@ -80,15 +86,15 @@ func (h *EventHandler) OnDelete(obj any) {
 
 // OnUpdate handles the endpoints update events.
 func (h *EventHandler) OnUpdate(oldObj, newObj any) {
-	oldEndpoints, ok := oldObj.(*v1.Endpoints)
+	oldEndpoints, ok := oldObj.(*discoveryv1.EndpointSlice)
 	if !ok {
-		logx.Errorf("%v is not an object with type *v1.Endpoints", oldObj)
+		logx.Errorf("%v is not an object with type *discoveryv1.EndpointSlice", oldObj)
 		return
 	}
 
-	newEndpoints, ok := newObj.(*v1.Endpoints)
+	newEndpoints, ok := newObj.(*discoveryv1.EndpointSlice)
 	if !ok {
-		logx.Errorf("%v is not an object with type *v1.Endpoints", newObj)
+		logx.Errorf("%v is not an object with type *discoveryv1.EndpointSlice", newObj)
 		return
 	}
 
@@ -100,15 +106,18 @@ func (h *EventHandler) OnUpdate(oldObj, newObj any) {
 }
 
 // Update updates the endpoints.
-func (h *EventHandler) Update(endpoints *v1.Endpoints) {
+func (h *EventHandler) Update(endpoints *discoveryv1.EndpointSlice) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
 
 	old := h.endpoints
 	h.endpoints = make(map[string]lang.PlaceholderType)
-	for _, sub := range endpoints.Subsets {
-		for _, point := range sub.Addresses {
-			h.endpoints[point.IP] = lang.Placeholder
+	for _, point := range endpoints.Endpoints {
+		if len(point.Addresses) == 0 {
+			continue
+		}
+		for _, address := range point.Addresses {
+			h.endpoints[address] = lang.Placeholder
 		}
 	}
 

zrpc/resolver/internal/kubebuilder.go

@@ -18,8 +18,8 @@ import (
 )
 
 const (
-	resyncInterval = 5 * time.Minute
-	nameSelector   = "metadata.name="
+	resyncInterval  = 5 * time.Minute
+	serviceSelector = "kubernetes.io/service-name="
 )
 
 type kubeResolver struct {
@@ -60,14 +60,19 @@ func (b *kubeBuilder) Build(target resolver.Target, cc resolver.ClientConn,
 	}
 
 	if svc.Port == 0 {
-		// getting endpoints is only to get the port
-		endpoints, err := cs.CoreV1().Endpoints(svc.Namespace).Get(
-			context.Background(), svc.Name, v1.GetOptions{})
+		endpointSlices, err := cs.DiscoveryV1().EndpointSlices(svc.Namespace).List(context.Background(), v1.ListOptions{
+			LabelSelector: serviceSelector + svc.Name,
+		})
 		if err != nil {
 			return nil, err
 		}
+		if len(endpointSlices.Items) == 0 {
+			return nil, fmt.Errorf("no endpoint slices found for service %s in namespace %s", svc.Name, svc.Namespace)
+		}
 
-		svc.Port = int(endpoints.Subsets[0].Ports[0].Port)
+		// Since this resolver is used for in-cluster service discovery,
+		// there should be at least one port available.
+		svc.Port = int(*endpointSlices.Items[0].Ports[0].Port)
 	}
 
 	handler := kube.NewEventHandler(func(endpoints []string) {
@@ -88,23 +93,27 @@ func (b *kubeBuilder) Build(target resolver.Target, cc resolver.ClientConn,
 	inf := informers.NewSharedInformerFactoryWithOptions(cs, resyncInterval,
 		informers.WithNamespace(svc.Namespace),
 		informers.WithTweakListOptions(func(options *v1.ListOptions) {
-			options.FieldSelector = nameSelector + svc.Name
+			options.LabelSelector = serviceSelector + svc.Name
 		}))
-	in := inf.Core().V1().Endpoints()
+	in := inf.Discovery().V1().EndpointSlices()
 	_, err = in.Informer().AddEventHandler(handler)
 	if err != nil {
 		return nil, err
 	}
 
-	// get the initial endpoints, cannot use the previous endpoints,
-	// because the endpoints may be updated before/after the informer is started.
-	endpoints, err := cs.CoreV1().Endpoints(svc.Namespace).Get(
-		context.Background(), svc.Name, v1.GetOptions{})
+	// get the initial endpoint slices, cannot use the previous endpoint slices,
+	// because the endpoint slices may be updated before/after the informer is started.
+	endpointSlices, err := cs.DiscoveryV1().EndpointSlices(svc.Namespace).List(
+		context.Background(), v1.ListOptions{
+			LabelSelector: serviceSelector + svc.Name,
+		})
 	if err != nil {
 		return nil, err
 	}
 
-	handler.Update(endpoints)
+	for _, endpointSlice := range endpointSlices.Items {
+		handler.Update(&endpointSlice)
+	}
 
 	r := &kubeResolver{
 		cc:     cc,